1. Field of the Invention
The present invention relates to a laser induced thermal imaging method and, more particularly, to a laser induced thermal imaging method which includes controlling aerial atmosphere in a device and annealing a transfer layer. The present invention relates to a laser induced thermal imaging for manufacturing of an organic EL display device.
2. Description of the Related Art
Of flat panel display devices, an organic light emitting display (“OLED”) device has a high response speed of less than 1 ms, is low in power consumption, and has no viewing angle problem due to its self-emitting characteristic, and so has an advantage as a moving image medium regardless of the size of the device. Also, the OLED can be manufactured using a simplified manufacturing process based on the existing semiconductor process technique and thus it attracts public attention.
The OLED display device is classified into a polymer type device using a wet-dry etching technique and a monomer device having a deposition technique according to its material and a process.
Of methods of patterning a polymer or monomer light emitting layer, an ink jet printing method has a disadvantage in that a material of organic layers except the light emitting layer is restricted and a structure for the ink jet printing should be formed on a substrate. Also, in case of patterning the light emitting layer using the deposition process, it has a difficulty manufacturing a large-size device due to use of a metal mask.
As an alternative technology of such a pattering method, a laser induced thermal imaging (“LITI”) has been recently developed.
The LITI is a technique that a laser generated from a light source is converted to heat energy and a pattern forming material is transferred to an object substrate using the heat energy to form a pattern. For the sake of the LITI, a donor element on which a transfer layer is formed and a substrate which is a subject are required. In the LITI, a donor film covers the acceptor substrate, and the donor film and the substrate are fixed to a stage.
The transfer layer is formed of an organic layer and has a characteristic of being so sensitive to oxygen and water vapor. That is, if the organic layer is exposed to oxygen and water vapor, life span of the organic layer is lowered or light emitting efficiency and life span are lowered if the organic layer includes a light emitting layer, thereby lowering life span and light emitting efficiency of the OLED.